Temperature-dependent electrical properties of B-site zinc substituted bismuth sodium titanate piezoceramics

Lead-free ceramics of B-site Zn substituted Bi0.5Na0.5TiO3, with the formula of (1 − x)Bi0.5Na0.5TiO3–xBi(Zn0.5Ti0.5)O3 (BNT–BZT, x = 0.01, 0.04, 0.07) have been prepared. These compositions have rhombohedral, rhombohedral–tetragonal morphotropic phase boundary, and tetragonal crystal structure, respectively. The polarization–electric field (P–E), bipolar and unipolar strain–electric field (S–E) curves of all the compositions are measured as the functions of temperature. The temperature-dependent values of the remnant polarization, maximum polarization, coercive field, bipolar and unipolar strain, as well as the shape change of P–E and S–E curves have been comparatively investigated and discussed. The observed different temperature-dependences of the above parameters are attributed to the fact that the introduction of BZN reduces the depolarization temperature and enhances relaxor characteristics, which is consistent with the temperature-dependent dielectric properties. These results are valuable in understanding and further designing noval BNT-based lead-free piezoelectric systems with high recoverable strain.